Advertising displays and posters often bear photographic reproduction of an object or objects offered for sale in a two-dimensional appearance. Such advertising displays and posters may be suitable for point of purchase displays, bill-boards, mall displays or home display, etc.
To a limited extent, thermoforming technology has been used in the past in conjunction with photographic imaging for creating bas-relief three-dimension displays. However, the results have been unimpressive due to distortion involved in translating from a two-dimensional image to a three-dimensional object, and vice versa.
There are three major forms of distortion that occur when a two-dimensional image derived from a single (primary) point of view is thermoformed over a three-dimensional topography. Of these three types of distortion, only one has been partially addressed by currently available technology. The effects of stretch and flow upon lettering colour boundaries, as plastic is thermoformed over a topographic mold is known in the prior art and has been partially corrected for a number of years. However, the method of such correction has not been found to be sufficiently accurate for creating detailed three-dimensional display devices. Furthermore, two other forms of distortion are equally important to the process of translating from two to three-dimensions, especially when incorporating a photographic rather than purely graphic image into a three-dimensional thermoform.
The second major form of distortion is known as parallax distortion or shadowing, and occurs when areas of a three-dimensional object cannot be recorded on a two-dimensional photograph because the line of sight from the primary point of view is obstructed by some portion of the object. After vacuum forming of the two-dimensional image over the three-dimensional mold, these areas of the final image are filled with information from adjacent regions by stretching of the thermoformable plastic sheet, resulting in a severe form of distortion.
The third major form of distortion is known as foreshortening, and occurs when areas of the three-dimensional object which are at an acute angle to the primary point of view are visually compressed and photographed onto a two-dimensional film. When the resulting image is vacuum formed over a topographic mold, the visually compressed information is not large enough to fill the topographic area from which it was derived, even taking into account the stretch and flow distortion which occurs in these areas.
Traditionally, the above discussed problems have been overcome by one of two methods. The effects of foreshortening and parallax distortion have been minimized by decreasing the amount of relief of the three-dimensional mold so that areas of sharp vertical relief, where the distortion is greatest, are substantially reduced. The effects of stretching on the contours and location of embossed lettering and simple colour boundaries have been overcome in the prior art by plotting the location of the lettering and other details on a blank sheet that has been thermoformed over a topographic mold. The sheet is then thermally flattened and the resulting distorted contours and locations are plotted using an overlay grid.